To increase the flexibility of 3C products (computers/communications/consumer products), various external devices can be connected using multi-media slots provided on the 3C products, to support devices such as external hard drives, portable disks or memory sticks (collectively referred to herein as USB drives), multi-media video and audio equipment, keyboards and so forth, so as to functional expansion of the 3C product. However, when 3C products initially came to rise, manufacturers designed various proprietary specifications for the transmission or communication interfaces for their own external devices. For example, many printers can only be connected to LPT ports, many MODEMs can only be connected to RS232 ports, certain types of mice and keyboards can only be connected to PS/2 ports, and so on. Moreover, different interface specifications require the installation of corresponding drivers and then rebooting the 3C products prior to use. Consequently, the external device must be compatible with the transmission interface of the 3C product. This can be the source of great inconvenience for the user. In addition, this introduces manufacturing difficulties for 3C product developers and accessory manufacturers.
The USB interface supports the convenient features of hot swapping and plug-and-play. This means that 3C products can be plugged/unplugged without powering off, which will not damage the host or USB device. Moreover, the USB protocol supports detection and use of newly plugged-in external devices in real time. Additionally, USB transmission speeds are much higher than those of traditional standard buses, such as a parallel ports (e.g. EPP, LPT) and serial ports (e.g. RS-232). Therefore, the USB interface has now become a popular and widely accepted specification.
To date, the development of the USB technology has gone through three major phases, from 1.0 to 3.0, and it is somewhat troublesome to change and maintain the USB socket built into the computer host. The USB 3.0 plug provides an engaging terminal on both sides. Inserted in either way, it can be electrically connected to the socket, which improves upon conflicting structural design on both sides. In this way, USB 3.0 expects to provide a more fool-proof design and avoid the damage of USB sockets due to a user's incorrect plugging or over-forcing of the plug. According to the current design, the electrically conductive terminals in the USB socket have a resilient structure. After the USB plug is connected to the socket, the resilient electrically conductive terminals in the USB socket are pressed back by the engaging terminals of the USB plug, and elastically abut against the engaging terminals. In this way, the electrical connection between the USB socket and USB plug is kept stable.
However, the resilient electrically conductive terminals may suffer from elastic fatigue, over-forcing or over-displacement, which can interrupt the electrical connection between the contact terminals and the resilient electrically conductive terminals. Powered-off or short-circuited USB device obviously cannot work effectively, which is, again, a source of great inconvenience to users. Moreover, many external devices are used collaboratively, such as multi-media video & audio equipment, keyboard and external hard drives, which must work together. In case of malfunction of the USB socket, users must resort to plugging and unplugging the external device again and again to maintain operations. Worse, this repeated plugging/unplugging operation may damage the external device more easily, and so users should be more cautious.
To maintain a convenient and hassle-free use, most users choose to change to a new USB socket. However, it is quite difficult for users to change the USB socket by themselves, which typically requires disassembling the 3C product and checking the motherboard. For most common users, who are unfamiliar with the internal structure of 3C products, they can only return the product to the manufacturer to change the USB socket, and this may take several days. Nowadays, people rely on 3C products so much that they may become annoyed if so much time is wasted on a small component, which introduces unwanted delays in their work or entertainment.
Because of the maintenance inconvenience related to USB sockets, manufacturers place a great emphasis on protecting them. With the current trend in which all electronic gadgets are made light, slim, short and small, the USB 3.0 is more compact than the previous USB 1.0 and 2.0, and looks like a mini or micro USB port. Yet, the number of terminals in USB 3.0 greatly exceed that of mini USB and micro USB. Unavoidably, the resilient electrically conductive terminals of USB 3.0 are still the core components susceptible to damage.